Polyolefins are hydrophobic and difficult to dye in that they lack dye sites to which dye molecules may become attached. One approach to color polyolefin fibers has been to add colored inorganic salts or stable organometallic pigments to polymer melts prior to fiber spinning. Nonvolatile acids or bases or materials such as polyethylene oxides or metal salts have been added to polymers prior to fiber formation to increase the affinity of the fiber for disperse, cationic, acid or mordant dyes. Polyolefin fibers are said to be grafted chemically with appropriate monomers after fiber formation to improve dyeability. Textile Fibers, Dyes, Finishes, and Processes: A Concise Guide, by Howard L. Needles, Noyes Publications, 1986, p. 191. An example of efforts to impart dyeability to polyolefins, and particularly polypropylene, has been nitrogen-based polymer additives. For example, in U.S. Pat. No. 3,361,843 issued to Robert Miller and Frederick C. Loveless on Jan. 2, 1968, various incompatible, basic nitrogen-based polymers are added to polypropylene, given a treatment with high concentrations of certain acidic chemical reagents and then dyed in an acid dye bath. U.S. Pat. No. 3,433,853 issued to Ralph H. Earle, Alfred C. Schmalz and Charles A. Soucek on Mar. 18, 1969 is similar. According to U.S. Pat. 3,653,803, issued to Clarence F. Hammer on Apr. 4, 1972, and assigned to a common assignee of U.S. Pat. No. 3,433,853, dyeing of the polypropylene fiber is somewhat improved by the method of U.S. Pat. No. 3,361,843, but processing of the fiber is difficult due to the incompatible polymer, the dye fastness properties are not reliably reproducible, and tinctorial strengths are not commercially sufficient. In U.S. Pat. No. 3,395,198 issued to Isaji Taniguchi et al. on Jul. 30, 1968, and U.S. Pat. No. 3,653,803, various compatible nitrogen-containing copolymers of ethylene and an aminoalkyl acrylate compound are disclosed which, when blended with polyolefins, render fibers formed from the blend acid dyeable. In U.S. Pat. No. 3,653,803, the compatible nitrogen-containing polymers are as disclosed in U.S. Pat. No. 3,395,198. In U.S. Pat. No. 5,017,658, issued to Takeshi Noma on May 21, 1991, a fiber finishing agent is used in melt spinning dyeable polypropylene fibers obtained by blending a copolymer of an ethylene aminoalkyl acrylate with polypropylene.
In U.S. Pat. No. 4,557,958, issued Dec. 10, 1985 to Edward D. Barkis, et al on Dec. 10, 1985, a blend of 70 weight percent polypropylene homopolymer and 30 weight percent ethylene-methylacrylate copolymer is applied to a fabric of woven polyolfin as a coating stripe to prevent fraying of the fabric when the fabric is cut.
In U.S. Pat. No. 4,853,290, issued to Apostol Yanidis on Aug. 1, 1989, a blend of ethylene-acrylic acid copolymer and ethylene-methylacrylate copolymer is coextruded onto a polypropylene film to serve as an adhesive or tie layer to a second polymer applied to it.
In U.S. Pat. No. 4,782,110, issued to James R. Wolfe, Jr. on Nov. 1, 1988, melt processible multi-phase thermoplastic compositions are described which can be formed into various shapes by compression molding, injection molding, blow molding and extrusion, and said to be useful for automotive parts, e.g. automotive boots, seals, gaskets, tubing, reinforced hose, film and sheeting. The composition comprises a blend of (a) 15-75 parts by weight of a crystalline polyolefin resin forming the continuous phase of the composition, and (b) 25-85 parts by weight of a crosslinked elastomer of an ethylene alkyl acrylate copolymer consisting essentially of units derived from ethylene, an alkyl ester of acrylic acid wherein the alkyl group contains 1-6 carbon atoms, and a monoalkyl ester of 1,4-butenedioic acid wherein the alkyl group contains 1-6 carbon atoms, forming the discontinuous phase of the composition.